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Avalanche Forecast

Archived

Dec 19th, 2024–Dec 20th, 2024

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Glacier.

A significant storm brought 40cms of new snow and strong winds, which is a perfect recipe for slab development.

Cautious route-finding and conservative decision-making is essential

Confidence

Moderate

Avalanche Summary

Avalanche control at Rogers Pass on Wednesday produced storm slab avalanches to size 3.

Several natural avalanches were observed in the highway corridor during the last storm. Naturals ran up to size 3 with some running running full feature.

Snowpack Summary

40cm of new snow has fallen with strong gusting Southerly winds. This lands on variable wind slabs already present in the Alpine and at Treeline. A persistent weak layer is down 50-70cm. This interface consists of surface hoar in sheltered locations, a sun crust on solar aspects, and continues to produce moderate-hard sudden results in test profiles. The snowpack's base is comprised of several early-season melt-freeze rain crusts.

Weather Summary

A pacific frontal system approaches BC and brings light snow to the Selkirks.

Tonight: 11cm, Alp low -4°C, Mod-Strong SW wind, Freezing level (FZL) 1500m

Fri: Trace precip, Alp High -1°C, Strong SW wind, FZL 1800m

Sat: 4cm. Alp High 0°C, Strong SW winds, FZL 1900m

Sun: Trace precip, Alp high -4°C, Moderate SW wind, FZL 1500m.

Terrain and Travel Advice

  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.